<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 行内元素 -> 块状元素 */
        /* a {
            display: block;
        } */

        /* 边距 */
        /* div {
            width: 200px;
            height: 100px;
            border-color: black;
            border-style: solid;
            border-width: 10px;
        } */

        /* 使边框不再撑大盒子 */
        * {
            box-sizing: border-box;
        }

        /* 内边距 */
        /* .inter {
            width: 200px;
            height: 100px;
            padding-left: 5px;
            padding-top: 5px;
            padding-right: 5px;
            padding-bottom: 5px;

            border-color: black;
            border-style: solid;
            border-width: 10px;
        } */
        /* 外边距 */
        /* div {
            border: solid green 5px;
            margin-top: 5px;
            margin-bottom: 5px;
            margin-left: 5px;
            margin-right: 5px;
        } */

        /* 块级元素水平居中 */
        /* div {
            border: solid green 5px;
            width: 200px;
            height: 100px;
            margin: auto;

            text-align: center;
        } */

        /* 弹性布局 */
        div {
            height: 700px;
            width: 700px;
            background-color: green;
            display: flex;
            /* justify-content: space-around; */
            align-items: space-around;
        }

        div span {
            height: 100px;
            width: 100px;
            background-color: red;
        }
    </style>
</head>

<body>
    <!-- <h1>行内元素 -> 块状元素</h1>
    <a href="#">链接1</a>
    <a href="#">链接2</a>

    <h1>盒模型: 边距</h1>
    <div></div>

    <h1>盒模型：内边距</h1>
    <div class="inter">内边距</div> -->

    <!-- <h1>外边距</h1>
    <div></div>
    <div></div>
    <div></div> -->

    <!-- <h1>块级元素水平居中</h1>
    <div>块级元素水平居中</div> -->

    <h1>弹性布局</h1>
    <div>
        <span>1</span>
        <span>2</span>
        <span>3</span>
    </div>
</body>

</html>